Mobile scaffold



July 25, 1967 1.. H. WI EBE MOBILE SCAFFOLD 3 Sheets-Sheet 1 Filed May 17, 1965 LOU/S H. W/EBE IN VE N TOR A TTORNEVS L H. WIEBE MOBILE SCAFFOLD July 25. 1967 3 Sheets-Sheet Filed May 17, 1965 /N VE N TOR M )M ATTORNEYS LOU/S H. WIEBE July 25. 1967 H. WIEBE 3,332,513

MOBILE S CAFFOLD Filed May 17, 1965 3 Sheets-Sheet 5 LOUIS h. W/EBf INVENTOR M114 fin M A 7'TORNEYS United States Patent 3,332,513 MOBILE SCAF FOLD Louis H. Wiebe, 42204 Road 52, Reedley, Calif. 93654 Filed May 17, 1965, Ser. No. 456,275 Claims. (Cl. 182-16) The present invention relates to a mobile scaffold having an elevatable worker support platform which is swingable through a predetermined arc of travel about an upright axis for positioning workmen adjacent to upright work objects and more particularly to such a scaffold wherein the axis of arcuate platform travel is shiftable on the scaffold to increase the range of such arcuate platform travel without moving the scaffold, In addition, the present invention provides a mobile scaffold which utilizes a plurality of such platforms permitting a greater range of movement and cooperative work between workmen on the platforms.

Heretofore, mobile scaffolds have mounted a worker support platform on an elevatable, rotatable boom which is secured to a stationary boom support post on the vehicle. Consequently, the platform is confined to a single predetermined arc of travel relative to its mounting vehicle and the adjacent work objects. In order to reach work objects beyond the predetermined arc of travel of the platform, the entire scaffold must be moved. This usually requires the workman to descend from the platform to operate the vehicle during such movement or the provision of an additional workman for operating the vehicle;

Accordingly, it is an object of the present invention to provide an improved mobile scaffold having a worker support platform capable of travel through an increased range of movement than prior art devices of this type.

Another object is to provide such an improved scaffold which is effective to reduce the number of scaffold moves in covering a particular work area.

Another object is to provide a mobile scaffold of the character described having controls which are conveniently operable by a workman on the platform.

Another object is to provide such a scaffold having a worker support platform elevationally rotatable through a predetermined arc abouta substantially upright axis on the mounting vehicle.

Another object is to provide a scaffold wherein the axis of arcuate travel of the platform is shiftable along the vehicle to increase the range of platform travel.

Another object is to provide an improved mobile scaffold which utilizes a plurality of independently movable platforms for greater range of platform positioning outwardly from the scaffold and cooperative Work between workmen on their respective platforms.

Other objects and advantages of the present invention will subsequently become more clearly apparent upon reference to the following description and accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of the mobile scaffold embodying the principles of the present invention.

FIG, 2 is a somewhat enlarged transverse vertical section through the mobile scaffold taken on line 2-2 of FIG. 1.

FIG. 3 is a somewhat enlarged fragmentary transverse horizontal section taken on line 33 of FIG. 2 showing a pair of boom support posts individually mounted on carriages within the chassis of the scaffold.

FIG. 4 is a somewhat enlarged longitudinal vertical section taken on line 4-4 of FIG. 2 showing a boom arm mounting in side elevation.

FIG. 5 is a somewhat reduced schematic view of the scaffold with several paths of platform movement traced 3,332,513 Patented July 25, 1967 about the scaffold in dashed lines to illustrate its operational capabilities.

FIG. 6 is a schematic diagram of the hydraulic control system for the scaffold of the present invention.

Referring more particularly to the drawings, a mobile scaffold embodying the principles of the present invention provides an elongated chassis 10 which is supported for earth traversing movement on a plurality of forward and rear-ward sets of wheels 11 and 12, respectively. The scaffold is powered by an engine 14 mounted on the chassis. The rear wheels 12 are driven through a transmission and drive shaft assembly generally indicated by the reference numeral 15. The front wheels 11 of the chassis are steerable through a set of steering links 16 having an hydraulic jack 18 disposed therein for control purposes.

The chasis 10 includes a lower box frame portion 20 mounting upwardly extended opposite forward and rearward end walls 22 and 23, respectively, inter-connected by opposite side walls 25, An upper deck or floor 27 is supported on the side and end walls and provides a pair of elongated transversely spaced substantially parallel slots 28 individually closely adjacent to the side walls 25. A pair of sets of tranversely spaced I-beams 30 are mounted on the lower box frame 20 with individual sets disposed beneath the slots 28. Each set of I-beams defines inwardly facing channels or tracks 32 extending longitudinally of the chassis between the opposite forward and rearward end walls.

As shown in FIG. 2, a pair of carriages 35 are individually disposed within the chassis beneath the slots 28. Since the carriages are identical, the same reference numerals are applied to their corresponding elements in the following description. Each of the carriages includes a substantially horizontal upper wall 36 and continuously depending opposite side wall portions 37. The carriages are supported for longitudinal movement in the chassis on a plurality of rollers 38 rollably engaging the tracks 32 of the I-beams 30. An hydraulic motor 42 is mounted on the inner surface of the outermost side wall 37 of each carriage by a bracket 43 secured thereto as by bolting,- welding, or the like. The hydraulic motor has an output shaft 45 rotatable about a substantially vertical axis which mounts a drive sprocket 47. An idler sprocket 50 is mounted in closely spaced coplanar relation to the drive sprocket by a bracket 52 connected to the same wall of the carriage as the bracket 43. The idler sprocket 50 is rotatable about a substantially vertical axis on a mounting shaft and nut assembly 53 on the bracket 52 with the axes of the sprockets disposed in a common vertical plane extending longitudinally of the chassis in spaced substan tially parallel relation to the I-beams 30.

An elongated chain 55 is associated with each of the carriages 35 and provides a forward end 56 connected to the forward end wall 22 of the chassis 10 and an opposite rearward end 57 connected to the rearward end wall 23 in transversely offset relation to the forward end. The chain has an intermediate run portion 58 which is tensioned between its opposite ends and is trained about the adjacent toothed peripheries of the drive sprocket 47 and the idler sprocket 50. This enables the chain and sprocket assemblies to serve substantially as a rack and gear to drive their respective carriages along their corresponding tracks 32.

1 An elongated tubular boom support post 60 is associated with each of the carriages 35 and has a lower end 62 extended through the upper wall 36 and is rigidly connected thereto by welding, as indicated at 63. The- 3 has a lower end 72 extended through the slot 28 and an opposite upper end 73. A toothed sprocket wheel 75 is mounted on the lower end of the sleeve and is spaced from the upper wall 36 of the carriage by a spacer ring 76 An hydraulic motor 80 is mounted in overhanging relation from the carriage 35 by a bracket 82 longitudinally extended outwardly from the upper wall 36. The motor mounts a drive sprocket 83 in coplanar relation to the sprocket 75 on the sleeve. An endless chain 85 is trained about the sprockets 75 and 83 and is tensioned in driving relation therebetween by an idler sprocket 86 rotatably mounted on the upper wall of the carriage.

An inverted substantially U-shaped strap 90 is mounted in upwardly extending relation on the upper end 73 of the sleeve 70 and has a centrally upwardly extended arm 92 secured thereto, as by welding or the like. A pair of boom mounting brackets 94 are mounted in outwardly extended relation on the sleeve intermediate its ends in substantially vertically aligned relation with a pair of jack mounting brackets 95 on the sleeve upwardly adjacent to the upper floor 27 of the chassis.

An elongated hollow boom arm provides a lower end 101 which is pivotally mounted on the brackets 94 for vertical swinging movement about a pivot bolt and nut assembly 103. The boom arm includes an opposite outwardly extended end 104 which pivotally mounts a worker support platform 106 by a pivot bolt and nut assembly 107. The platform is maintained in substantially horizontal position during elevational swlinging movement of the arm by an elongated rod 110. The rod has a lower end 112 pivotally mounted on the arm 92 of the sleeve 70 and an opposite upper end 114 pivotally mounted on the platform 106 by a pivot bolt and nut assembly 115. In such position, the rod is disposed in spaced parallel relation from the boom arm to form therewith a parallelogram linkage between the platform and the mounting sleeve 70. The vertical swinging movement of the arm is obtained through actuation of an hydraulic jack having a cylinder end 122 pivotally mounted on the brackets 95 on the sleeve and an opposite rod end 123 pivotally connected to a bracket 125 on the arm.

As best shown in FIG. 6, the hydraulic control system for the scaffold of the present invention provides a forward and reverse drive control lever 127 and a steering lever 128. The levers are mounted on the upper end of an elongated substantially upright pedestal 30 disposed adjacent to the forward end wall 22 of the chassis and intermediate the slots 28. The forward and reverse control lever is mechanically connected to a double actuating valve 132 and the steering control lever 128 is separately connected to a similar valve 133. An hydraulic pump is mounted on the chassis 10 and is driven by the engine 14. The pump includes a suction line 142 which is connected to an hydraulic fluid tank 143. A high pressure supply conduit 145 is extended from the pump for connection to one side of the valves 132 and 133. A pair of conduits 146 and 147 are extended from the steering valve 132 for connection to the respective opposite ends of the steering cylinder 18 for alternate extension and retraction during steering. A return line 148 is extended from the steering valve for alternately draining the conduits 146 or 147.

The forward and reverse control valve 133 is connected to the supply conduit 145 and has a pair of conduits 150 and 151 extended therefrom for connection to an hydraulic motor 152 having driving connection to the rear wheel drive assembly 15. A boom rotation control valve 155 is mounted on the platform 106 and is controlled through a mechanical linkage by a lever 156 on the upper portion of the platform. A pair of conduits 157 r and 158 are extended from the valve and are connected to the hydraulic motor 80 on the carriage. A return line 159 is extended from the valve 155 for communication with the tank 143. A boom elevating valve 160 is mounted on the platform and is controlled by a foot-operated pedal 162 on the floor of the platform. A pair of conduits 164 and 165 are extended from the boom elevating valve and individually connected to the opposite ends of the hydraulic jack 120. A return line 166 is extended from the valve 160 and connects with the return line 159 of valve 155.

A support post shifting valve 170 is mounted on the platform for actuation by a foot pedal 172 adjacent to the pedal 162 on the platform. A pair of conduits 174 and 175 are extended from the valve to the hydraulic motor 42 on the carriage. A return line 176 is extended from the valve and connected to the return line 159 of the valve 155. A branch conduit 180 from the main supply conduit 145 from the pump 140 is connected to a plurality of supply conduits 183, 184 and 185 which individually connect to the valves 155, 160 and 170, respectively. A centrally disposed upright tubular pipe is upwardly extended from the floor 27 of the chassis for receiving therethrough the supply conduits 183, 184 and 185 and the return conduits 159. As best shown in FIG. 1, these conduits are extended downwardly through the upper end of the sleeve 70 and thence through the hollow boom arm 100 for connection to their respective valves. An abundance of slack is provided in the conduits between the upper end of the pipe and the sleeve to permit full swinging movement of the arm and platform between its extreme positions. An elongated tension spring 192 is connected between the slack portion of the conduits and the upper end of the pipe to maintain the conduits in a desired elevated position above the chassis 10 when not tensioned by the movement of the boom arm.

Operation The operation of the described embodiment of the subject invention is believed to be clearly apparent and is briefly summarized at this point. The scaffold of the present invention is usually motivated to the work area with the platforms 106 and boom arms 100 disposed in the lowered dashed line position of FIG. 1 with the platforms closely adjacent to the control valve pedestal 130. In such position, a workman disposed on either of the platforms is able conveniently to reach the forward and reverse control lever 127 and the steering control lever 128.

Upon reaching the work area, the platforms and boom arms may be raised by actuation of their respective pedals 162 to shift the corresponding control valve 160 to a position permitting hydraulic fluid under pressure from the main supply conduit 145, branch conduit 180, and supply conduit 184 to be directed through the conduit 164 connected to the head end of the jack 120. Such pressurization of the head end of the jack extends the rod end 123 thereof to elevate the boom arm and platform. Fluid in the rod end of the cylinder is exhausted from the conduit 165 and returns to the reservoir tank 143 by way of the return line 166.

After reaching the desired height, either of the platforms 106 and boom arms 100 may be rotated in either direction by actuation of the lever 156 on the platforms to shift the rotary valve 155 controlling the appropriate hydraulic motor 80. The motor may be driven in either direction depending upon manipulation of the control lever which, through its drive sprocket 83, rotates the sprocket 86 on the lower end of the boom mounting sleeve 70. As best shown in FIG. 5, each of the platforms is movable through an arc of travel of approximately 270 beginning from a position longitudinally aligned with its respective slot 28 in the upper floor 27 of the chassis to an opposite extreme position extended across and outwardly from the opposite side of the chassis. With both support sleeves 70 disposed in substantially transversely aligned relation at the same end or at corresponding positions along the slots 28 the platforms can be positioned in closely disposed relation to each other for providing optimum cooperative work between the workmen on their respective platforms.

The above described rotating range of platform movement can be effectively increased by actuation of the hydraulic motor 42 on the carriage 35. This is accomplished by depression of the foot pedal 172 on the platforms 106 to position the valve 170, permitting hydraulic fluid under pressure to flow through the appropriate conduit 174 or 175 to the hydraulic motor 42. Upon such actuation, the drive sprocket 47 is rotated in traversing relation to the run portion 58- of the chain 55. This movement motivates the carriage along the tracks 32 longitudinally to shift the support posts 60 and boom arm support sleeve 70 through the slot 28 in the floor 27 of the chassis. The carriage may be stopped anywhere along the slot and the boom arm and platform elevationally or rotatably manipulated, as described above, to any desired position within the arc of travel shown in FIG. 5. During movement of the platform, the hydraulic supply conduits 18 3, 184 and 185 are provided sulficient slack to accommodate such movement by their extension from the pipe 190' which precludes entanglement of the conduits with other scaffold components on the chassis.

In view of the foregoing, it is readily apparent that the structure of the present invention has provided an improved scaffold having a range of platform movement covering a greater work area than heretofore possible with conventional structures. The scaffold of the present invention utilizes a pair of worker support platforms which provide closely related work positions for improved cooperative work between workmen on the platforms. Furthermore, the scaffold is conveniently controlled from the operators platform so as to eliminate the need for additional workmen to control the scaffold during movement between work areas.

Although the invention has been herein shown and described in what is conceived to .be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not'to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is: I

1. A mobile scaffold comprising a chassis; boom support means extended upwardly from the chassis for rotation about a substantially upright axis; an elongated boom arm having an end pivotally mounted on said support means for rotation therewith and for vertical swinging movement about a substantially horizontal axis and including an opposite extended end; a worker support platform mounted on said extended end of the arm for movement through a predetermined range of arcuate travel about said axis of the support means; a carriage rotatably mounting said suuport means on the chassis for reciprocal movement along a predetermined substantially horizontal path; an elongated flexible reaction member having opposite ends individually connected to said chassis at positions spaced longitudinally of the path and offset transversely of the path; powered rotary drive means borne by said carriage having the reaction member tensioned thereagainst with portions of said member on opposite sides of the drive means being offset from each other transversely of the path and disposed in substantially parallel relation to the path, the drive means providing an upright axis disposed substantially midway between said parallel portions of the reaction member and the drive means having driving connection to said reaction member for unitary rectilinear travel of said carriage, support means, arm and platform along the chassis to increase the effective range of the platform, and powered means mounted on said carriage having rotatable driving connection to said boom support means to permit unrestricted travel of said carriage on the chassis.

2. A mobile scaffold comprising a chassis; boom support means extended upwardly from the chassis for rotation about a substantially upright axis; an elongated boom arm having an end pivotally mounted on said support means for rotation therewith and for vertical swinging movement about a substantially horizontal axis and including an opposite extended end; a worker support platform mounted on said extended end of the arm for move ment through a predetermined range of arcuate travel about said axis of the support means; a carriage rotatably mounting the support means in said upwardly extended position; an elongated track borne by the chassis reciprocably mounting the carriage thereon; an elongated flexible drive reaction member having opposite ends individually connected to said chassis at positions in spaced relation longitudinally of the track and offset transversely of the track; powered drive means borne by said carriage including a rotary member rotatable about an upright axis disposed substantially midway between the positions of connection of the opposite ends of the reaction member measured transversely of the track and said drive means having longitudinally traversing driving connection to said reaction member for rectilinear travel of the carriage along the chassis whereby said predetermined arcuate platform movement is attainable from any position of the support means along the chassis, and powered means mounted on said carriage having rotatable driving connection to said boom support means to permit unrestricted travel of said carriage on the chassis.

3. A mobile scaffold comprising an elongated wheeled chassis having opposite ends; an elongated track extended between said ends of the chassis; a boom support post extended upwardly from the chassis for rotation about a substantially upright axis; an elongated boom arm having an end pivotally mounted on said support post for rotation therewith and for vertical swinging movement about a substantially horizontal axis and including an opposite extended end; a Worker support platform mounted on said extended end of the arm for movement through a predetermined range of arcuate travel about said axis of the support post; a carriage having a plurality of wheels rollably engaging the track rotatably mounting said support post in said upwardly extended position; an elongated flexible chain having opposite ends individually connected to said opposite ends of said chassis with said ends offset laterally of the chassis, the chain being of a length somewhat longer than the distance between the points of connection thereof to the chassis to provide a predetermined amount of slack in the chain; and a powered drive sprocket mounted on the carriage providing a substantially erect axis of rotation disposed in an upright plane extended longitudinally of the chassis substantially midway between a pair of upright planes extended longitudinally of the chassis individually through said ends of the chain and said sprocket intermeshing with the chain continually to tension the same between said points of connection and during rotation effecting unitary rectilinear travel of said carriage, support post, arm and platform along the chassis whereby said predetermined arcuate platform travel is attainable from any position of the support post along the chassis.

4. A mobile scaffold comprising an elongated wheeled chassis having opposite ends; an elongated track extended between said ends of the chassis; a boom support post extended upwardly from the chassis for rotation about a substantially upright axis; an elongated boom arm having an end pivotally mounted on said support post for rotation therewith and for vertical swinging movement about a substantially horizontal axis and including an opposite extended end; a worker support platform mounted on said extended end of the arm for movement through a predetermined range of arcuate travel about said axis of the support post; a carriage having a plurality of wheels rollably engaging the track rotatably mounting said support post in said upwardly extended position; a powered drive sprocket mounted on the carriage and rotatable about a predetermined axis; an elongated flexible chain providing opposite ends individually connected to the ends of the chassis in transversely spaced off-set relation and disposed in meshing relation to said drive sprocket; and an idler sprocket rotatably mounted on the carriage for rotation about an axis disposed in spaced substantially parallel relation to the axis of the drive sprocket and meshing with the opposite side of the chain from the drive sprocket to maintain the chain substantially parallel to the track for unitary rectilinear travel of said support post, arm and platform along the chassis incident to rotation of the drive sprocket whereby said predetermined arcuate platform movement is attainable from any position of the support post along the chassis.

5. A mobile scaffold comprising a mobile chassis having opposite ends, a carriage mounted on the chassis for movement in a predetermined path thereon between the ends of the chassis, a workman support mounted on the carriage for adjustable positioning with respect to said chassis, powered means borne by the carriage having position controlling connection to the support and providing control means on the support, and powered means having position controlling connection to the carriage and providing control means on the support.

6. A mobile scaffold comprising a vehicle supported for earth traversing movement, a carriage mounted on the vehicle for rectilinear movement in a predetermined path thereon, a workman support mounted on the carriage, an elongated flexible reaction member having opposite ends anchored to the vehicle at positions spaced longitudinally of said path, and rotary drive means borne by the carriage and engaged with the reaction member intermediate opposite ends thereof, said reaction member being tensioned about a portion of the drive means with portions of said reaction member on opposite sides of said drive means being offset and disposed in substantially parallel relation to said path and to each other.

7. The scaffold of claim 6 in which the reaction member is a chain and the opposite ends thereof are anchored at positions offset transversely of the path, and the drive means includes a drive sprocket mounted for rotation about a substantially erect axis and in mesh with the chain.

8. The scaffold of claim 7 including an idler borne by the carriage and engaged with the chain opposite to the drive sprocket therefrom and holding said chain in mesh with the drive sprocket.

9. A mobile scaffold comprising an elongated chassis; boom support means extended from the chassis for rotation about a predetermined axis; an elongated boom arm having an end mounted on said support means and an opposite extended end; a worker support platform mounted on said extended end of the arm for movement through a predetermined range of arcuate travel about said axis; movable support means borne by the chassis mounting said boom support means, arm and platform for unitary rectilinear longitudinal travel along the chassis to increase the effective extendible range of the platform in all directions outwardly from the chassis; and powered means mounted on said movable support means having rotatable driving connection to said boom support means to permit unrestricted travel of said movable support means along the chassis.

10. A mobile scaffold comprising an elongated chassis having opposite ends; a boom support means extended upwardly from the chassis for rotation about a predetermined axis; an elongated boom arm having an end pivotally mounted on said support means for rotation therewith and for swinging movement about an axis substantially normal to the axis of the support means and including an opposite extended end; a worker support platform mounted on said extended end of the arm for movement through a predetermined range of arcuate travel about said axis of the support means; a movable support mem ber borne by the chassis mounting said boom support means, arm and platform for unitary rectilinear longitudinal travel along the chassis between its ends to increase the effective extendible range of the platform in all directions outwardly from the chassis; and powered means mounted on said support members having rotatable driving connection to said boom support means to permit unrestricted travel of said support member between the ends of the chassis.

References Cited UNITED STATES PATENTS 2,450,812 10/1948 Ray 182-13 2,616,768 11/1952 Stemm 182-2 2,787,278 4/1957 Mitchell 182-2 2,798,623 7/1957 Girardi 182-2 2,996,141 8/1961 Eitel 182-2 3,127,952 4/1964 Baerg 182-2 FOREIGN PATENTS 759,449 10/ 1956 Great Britain.

REINALDO P. MACHADO, Primary Examiner. 

9. A MOBILE SCAFFOLD COMPRISING AN ELONGATED CHASSIS; BOOM SUPPORT MEANS EXTENDED FROM THE CHASSIS FOR ROTATION ABOUT A PREDETERMINED AXIS; AN ELONGATED BOOM ARM HAVING AN END MOUNTED ON SAID SUPPORT MEANS AND AN OPPOSITE EXTENDED END; A WORKER SUPPORT PLATFORM MOUNTED ON SAID EXTENDED END OF THE ARM FOR MOVEMENT THROUGH A PREDETERMINED RANGE OF ARCUATE TRAVEL ABOUT SAID AXIS; MOVABLE SUPPORT MEANS BORNE BY THE CHASSIS MOUNTING SAID BOOM SUPPORT MEANS, ARM AND PLATFORM FOR UNITARY RECTILINEAR LONGITUDINAL TRAVEL ALONG THE CHASSIS TO INCREASE THE EFFECTIVE EXTENDIBLE RANGE OF THE PLATFORM IN ALL DIRECTIONS OUTWARDLY FROM THE CHASSIS; AND POWERED MEANS MOUNTED ON SAID MOVABLE SUPPORT MEANS HAVING ROTATABLE DRIVING CONNECTION TO SAID BOOM SUPPORT MEANS TO PERMIT UNRESTRICTED TRAVEL OF SAID MOVABLE SUPPORT MEANS ALONG THE CHASSIS. 